Bags for reference fluids are widely used in connection with analytical instruments. The bags are frequently delivered in containers, e.g. a cassette, wherein several bags are delivered in one cassette.
It is common for reference fluid bags to contain gases such as CO2 and O2. Therefore, it is necessary for a reference fluid bag to be a sealed unit such that gas cannot enter or escape the contents of the bag, i.e. there is no fluid communication between the interior and exterior of the bag. This is important so that the relative concentrations of components, particularly gaseous components, in the bag are kept at the desired concentration.
An object of the invention is to provide an improved reference fluid bag for the calibration and/or quality control of a creatine and/or creatinine sensor. In particular, it is an object of the invention to provide a reference fluid bag resulting in improved calibration and/or quality control of a creatine and/or creatinine sensor.